self-fulfilling 
adjective
(Of an opinion or prediction) bound to be proved correct or to come true as a result of behaviour caused by its being expressed: expecting something to be bad can turn out to be a self-fulfilling prophecy...
- Some have warned that labelling children in this way can be counterproductive, perhaps proving to be a self-fulfilling prophecy.
- Williams told everyone who would listen that his players were useless, and it eventually proved to be a self-fulfilling prophecy.
- Reportedly, he has said he is to be a one-term prime minister, which may prove to be a self-fulfilling prophecy.
